linux-kernel - Re: [PATCH] net/smc: Fix possible leaked pernet namespace in smc

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Date:   Tue, 1 Nov 2022 19:07:11 +0800
From:   Chen Zhongjin <chenzhongjin@...wei.com>
To:     Tony Lu <tonylu@...ux.alibaba.com>
CC:     <linux-kernel@...r.kernel.org>, <linux-s390@...r.kernel.org>,
        <netdev@...r.kernel.org>, <kgraul@...ux.ibm.com>,
        <wenjia@...ux.ibm.com>, <jaka@...ux.ibm.com>,
        <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <guvenc@...ux.ibm.com>
Subject: Re: [PATCH] net/smc: Fix possible leaked pernet namespace in
 smc_init()

Hi,

On 2022/11/1 19:00, Tony Lu wrote:
> On Tue, Nov 01, 2022 at 05:37:22PM +0800, Chen Zhongjin wrote:
>> In smc_init(), register_pernet_subsys(&smc_net_stat_ops) is called
>> without any error handling.
>> If it fails, registering of &smc_net_ops won't be reverted.
>> And if smc_nl_init() fails, &smc_net_stat_ops itself won't be reverted.
>>
>> This leaves wild ops in subsystem linkedlist and when another module
>> tries to call register_pernet_operations() it triggers page fault:
>>
>> BUG: unable to handle page fault for address: fffffbfff81b964c
>> RIP: 0010:register_pernet_operations+0x1b9/0x5f0
>> Call Trace:
>>    <TASK>
>>    register_pernet_subsys+0x29/0x40
>>    ebtables_init+0x58/0x1000 [ebtables]
>>    ...
>>
>> Fixes: 194730a9beb5 ("net/smc: Make SMC statistics network namespace aware")
>> Signed-off-by: Chen Zhongjin <chenzhongjin@...wei.com>
> This patch looks good to me.
>
> The subject of this patch should be in net, the prefix tag is missed.

Thanks for review and remind! I will add net tag for the next time I 
send patch to netdev.


Best,

Chen

>
> Reviewed-by: Tony Lu <tonylu@...ux.alibaba.com>
>
>> ---
>>   net/smc/af_smc.c | 6 ++++--
>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
>> index 3ccbf3c201cd..e12d4fa5aece 100644
>> --- a/net/smc/af_smc.c
>> +++ b/net/smc/af_smc.c
>> @@ -3380,14 +3380,14 @@ static int __init smc_init(void)
>>   
>>   	rc = register_pernet_subsys(&smc_net_stat_ops);
>>   	if (rc)
>> -		return rc;
>> +		goto out_pernet_subsys;
>>   
>>   	smc_ism_init();
>>   	smc_clc_init();
>>   
>>   	rc = smc_nl_init();
>>   	if (rc)
>> -		goto out_pernet_subsys;
>> +		goto out_pernet_subsys_stat;
>>   
>>   	rc = smc_pnet_init();
>>   	if (rc)
>> @@ -3480,6 +3480,8 @@ static int __init smc_init(void)
>>   	smc_pnet_exit();
>>   out_nl:
>>   	smc_nl_exit();
>> +out_pernet_subsys_stat:
>> +	unregister_pernet_subsys(&smc_net_stat_ops);
>>   out_pernet_subsys:
>>   	unregister_pernet_subsys(&smc_net_ops);
>>   
>> -- 
>> 2.17.1